The 7950 GX2 is okay. A waste of money if you ask me. Becides, it's not really the fastest single card solution. It's the fastest dual-PCB in one package solution. Technically it's two 7900 GTX's mounted together and linked with a special PCI-E bus.
The dual GPU GX2 is a good card as it leads the way among all video cards when performing at 1920x1200 resolution regardless of dual GPU or single, but the ATI X1900XTX video card is faster overall. It even outperforms the Geforce 7950 GX2 in most tests.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?